The present invention relates to the field of optical devices. More particularly, the present invention relates to tiling a plurality of arrays of optical devices configured for imaging with higher resolution than provided by a single array.
Print and display resolution has become a critical parameter in the design of imaging systems. From paper print, photo print and display, industries are demanding higher and higher resolutions for a wide range of imaging applications. Besides the higher resolution, there is also a demand for reproducing images with minimal artifacts, distortions and/or other defects.
One solution for the demand of high fidelity and high resolution print and display imaging has been to use imaging systems capable of generating images with a greater number of smaller pixels. In certain applications, pixels are configured as a linear, or substantially linear, arrays of pixels for generating an image line on a display unit or print medium.
Optical MEM (micro-electro-mechanical) devices are useful in imaging technologies. Examples of optical MEM devices that can be used in imaging technologies are disclosed in the U.S. Pat. Nos. 5,311,360, 5,841,579 and 5,808,797, all issued to Bloom et al., the contents of which are hereby incorporated by reference.
Briefly, optical MEM devices described in the above referenced patents have one or more sets of movable ribbons that comprise a support layer and a reflective top-layer. The support layer is preferably a silicon nitride layer and the reflective top-layer is preferably an aluminum layer. The ribbons are coupled to a substrate at opposite ends of the ribbons, whereby center portions of the ribbons (active portions) move up and down to modulate an incident light source. Imaging with the aforementioned optical MEM devices offers the capability of generating high contrast, high resolution images efficiently within a compact circuit package. In certain applications, each pixel within an image is formed with three or more sets of ribbon pairs.
What is desired is a method of making an array of optical MEM devices for imaging which is capable of generating image lines with high resolution while minimizing artifacts, distortions, and/or other defects.
Embodiments of the invention are directed to optical devices, arrays of optical devices and related methods. In accordance with the embodiments of the invention, an optical device preferably comprises an array of addressable optical MEM devices having ribbon pairs for modulating a light source. The array of ribbon pairs are grouped into a center group and end groups. The center group has sets of ribbon pairs, such as three ribbon pairs per set, that are collectively addressed to image pixels. The end groups have fractional sets of ribbon pairs, such as one pair of ribbons per set, that are addressed to image sub-pixels. The optical MEM device preferably comprises bond pads corresponding to each set and fractional set of ribbon pairs for coupling to a driver circuit. It will be apparent to those of ordinary skill in the art that optical devices other than MEM devices can be used including arrays of liquid crystal display (LCD) pixels. In such a case, a sub-pixel of an LCD would be formed of a separately addressable LCD device which is reduced in size relative to an LCD pixel. The present invention can be implemented using an LCD formed using any conventional LCD technology.
The ribbons are preferably elongated ribbons formed from silicon-based materials, such as silicon-nitride, silicon-oxide and combinations thereof. The ribbons preferably have layers of reflective material, such as aluminum, for reflecting light from the top surfaces of the ribbons. The ribbons can have any dimension suitable for the applications at hand, but preferably have lengths in a range of about 50 to about 500 microns and widths in a range of about 4.0 to about 40 microns and are capable of modulating light having at least one wavelength in a range of about 300 to about 3000 nanometers.
An apparatus, in accordance with embodiments of the invention, comprises one or more linear arrays of optical MEM devices for generating pixels in an image line. The array comprises a first row of optical MEM devices and a second row of optical MEM devices that are tiled in a staggered configuration with respect to the first row, such that end groups of ribbons, as described above, form overlap regions for generating pixels in the image line. In accordance with further embodiments, the apparatus comprises a third row of optical MEM devices staggered relative to the first row and/or second row. In yet further embodiments, the apparatus comprises a display means, such as a screen or a monitor for displaying image lines and/or a print means for printing image lines onto a suitable print medium.
In accordance with the method of the invention, optical MEM devices configured for generating pixels and end sub-pixels are tiled (arranged) in an array, with the ends forming overlap regions, as described above. A test image is generated from the array and selected end sub-pixels, or sub-pixels and pixels, are disabled or suppressed to optimize the image quality and/or tailor the image quality for the intended application. Preferably, selected sub-pixels are disabled to remove artifacts and defects and to maximize pixel density of the image line corresponding to the overlap regions.